Die set



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DIE SET April 15, 1941. E. A. aqLmissxczl-l Filed June l7 1940 Patented pr. 15, 1.941

UNITED STATES PATENT OFFICE Dm sE'r Emil A. Baumbach, Chicago, Ill. Application June 17, 1940, serial No. 340,911

12 Claims.

This invention relates to punch and die sets, and more particularlyto an improved leader pin and leader pin bushing construction for aligning the relatively movable parts of such sets.

In punch-and ydie sets, the life of the punches and dies used therein and the accuracy of the Work accomplished are directly affected by the accuracy of alignment of the respective moving parts of the set, and morepar-ticularly by the manner in which this alignment is retained over a long period of time. It is therefore an object of the 4present invention to provide a punch and die set in which the respective parts are secured and retained in extremely accurate relative positioning, and wherein such accuracy may be retained over long periods of continual use.

The usual punch and die set comprises a die shoe and punch holder Iand two or more .leader pins secured tothe die shoe and having bearing surfaces. in the punch holder to keep the respective parts in alignment during their relative movement to and from each other. In such prior leader pin sets, it has `heretofore been 'proposed that the movable 'punch holder be provided with bushings which are embedded in the punch holder, and in which the leader pins slide. These bushings and the leader pins upon which they slide are ordinarily tightly forced into holes drilled into the punch holderand die shoe respectively. Of course, any alignment thus obtained is dependent upon the accuracy with which the holes into which the parts are to be forced have been drilled. vA powerful arbor press or the like is ordinarily employed in order to force the bushings and pins into their yrespective holes with a tight iit, and thus such installation is ordinarily permanent and not easily changed. With bushings installed in this manner it is diflicult to replace the bushings, as the holes are apt to have been so stretched during the forcing process that they have lost their alignment and must again be machined and straightened and oversize bushings then employed.

It will be seen that accurate alignment oi the leader pins `and bushings by the methods heretofore employed is extremely 'diflicult It is well known that by the use of ordinary drills, it is hard to provide holes of any reasonable degree of accuracy, and that such holes can be obtained.

dinarily or easily obtained with the leader `pin and bushing constructions and methods of assembly heretofore common. It is therefore an object of the present invention toprovidea die y set construction which is not subject 4to the limitations and difficulties' above discussed, and wherein alignment is more jreadily achieved.

Furthermore, in driving 'the usual leader pin bushing into .thelpunch holder, the bushing islapt to be compressed or contracted `so as lto render the inner bear-ing surface thereof out of round, bell-mouthed, or irregular. This force may .also stretch `or distort the holes in the punch hol-der, altering the accuracy of their alignment `with the leader pins. f

The present invention contemplates the provision of readily removable and replaceable leader pins and leader pin bushings which may be .in-

stalled and removed -by the .use of the usual inexpensive hand toolsv and vwithout necessity for a powerful arbor -press or the like to force the bushings into or out `ofthe punch holder.

An additional feature of the present invention is the ease with which the bushings maybe Isecured in fixed relation yto thelunder surface of the punch holder and with reach other, so 'that after the punch holder and die shoes are in place and the set assembled, the nal and .accurate adjustment Vof the bushings with the punch holder can be made and the parts then :securely locked in place.

A further `object of the present invention is to increase the contact yarea or bearing surface of the bushings .with the Vleader pin Without intertering with .or reducing the working area of the die set.

Still vanother object of the present inventio is to provide a leader pin and leader pin :bushing construction comprising a plurality .of elements. adapted to be permanently. secured together vto forma unitary leader pin or leader pin bushing.

To this `end the component `parts are so formed .as to .permit assembly vand .subsequent finishing of the important valigning surfaces, which finishing operation eliminates all inaccuracy caused by the assembling operation.

Itis also an .object nf the present :invention to provide means whereby separate flanges 'may readily be .attached to leader pins .or .leader pin bushings with a minimum of time and effort.

Because of the greater accuracy achieved 1Joy the use of dowel pins to align adjacentsuriaces, provision has been made :in the present .invention for the'use of such-dewel pins for aligning both leader pin and leader pin bushings in conjunction with the securing means employed with each of these elements. It is therefore an object to provide a leader pin construction in which dowel pins may be employed to vaid in positioning the various parts.

Other objects and advantages will hereinafter more fully be described, and for a complete understanding of the nature, scope, and characteristics of this invention, reference may now be had to the `following description and accompanying drawing, in which latter:

Fig. 1 is an elevation, partially in section, of a die set embodying the present invention.

Fig. 2 is a perspective view from above of the preferred type of leader pin used in the present invention.

Fig. 3 is a bottom view of the leader pin shown' pins 3. These leader pins 3 are secured to the die shoe 2 and slidably engage the leader pin bushings 4, as indicated, so that the punch holder may reciprocate Within the bushings, keeping the punch holder relatively positioned through- 'out its reciprocation.

'Ihe leader pins 3 may each be provided with peripheral flanges 5, which may be integral or may be secured to their respective leader pins in the manner hereinafter described in detail. These flanges both have a lower surface 6 which has been machined so as to :be absolutely perpendicular to the axis of the respective leader pin, and which is positioned so as to bear against a correspondingly accurately machined upper surface I of the die shoe.

To roughly position the leader pin in the die shoe, the lower depending end 8 thereof is first inserted into a hole 9 in the die shoe, and which is positioned at the approximate desired positioning of the leader pin. Dowel pins I0 may subsequently be inserted through suitable holes II in the flanges 5 to retain the selected positioning of the leader pin in the die shoe. After this positioning has been obtained, suitable securing means, `such as the hollow-head screws I2, may be inserted through the holes I3 in the flange 5.

It will be noted that in order to position the leader pins accurately at an angle perpendicular to the upper surface 'I of the die shoe, it is essential that the under surfaces 6 of the flanges be absolutely perpendicular to the central axis of their respective leader pins. To secure and retain this relationship, theV present invention employs a novel method of combining the pin and plate or flange 5. In this method the parts are so made that the pin is about .002" oversize. The parts are then forced together with a press fit and a groove I4 surrounding the lower portion of the leader pin is caused to register with a complemental internally disposed groove I5 positioned on the inside of the central opening in' the flange 5. At that time, there may be some distortion of the flange as an incident to' the forcing process. To remove any possibility` of this distortion, the under surface 6 of the rflange may, after assembly, be ground to an accurate surface exactly perpendicular to the axis of the leader pin 3. By this means any possibility of irregularity or inaccuracy in this structure is eliminated, and when the ange is .secured to the fiat upper surface 'I of the die shoe 2 the leader pin, being perpendicular to the machined surface of the flange, is fixed in a position perpendicularl to that surface.

It will be apparent that inasmuch as the entire surface 'I with which the under surface 6 of both leader pin flanges is in contact is made by the same manufacturing operation, an essentially plain, nat surface is provided on the upper part of the die shoe. Therefore, both leader pins will be oriented in a vertical position in exact parallel apposition, and with the leader pins secured by means of dowel pins I0 and suitable securing means, an accurate and permanent parallelism of these parts is assured.

The manner of securing the leader pin bushings 4 to the under side of the punch holder is very similar to that just described. The leader Y pin bushings may be provided with annular ciry cumferential grooves I6 which are adapted to register with similar grooves I'l positioned on the inside of annular flanges I8. The bushings may be provided adjacent one end with a charnfer or beveled edge I9, and in assembly this beveled edge may be employed to initiate movement of the leader pin bushing into the flange when installed with a press t.. The flange is then moved over the outside of the bushing until the grooves I6 and I1 register.

After the leader pins and bushings have each been provided with a ange so that the grooves I4, I5, and I6, I1 are in alignment, they may be retained in such positioning by a ring of metal or the like which may be poured in a molten state into the hollow spaces formed by these grooves through the holes 20 and 2I (Figs 2 and 3) in the leader pin flange and 22 and 23 (Figs. 4 and 5) in the leader pin bushing flange, and which communicate with the grooves on the inside of the flanges. One of these openings may serve as a vent while the iiowable material is being introduced through the other. Though any suitable metal may be used, it has Oi been found that either zinc or bronze is preferthe bushing in the same manner as the leader pin flanges are ground.

The manner of positioning and securing the leader pin bushings in the punch head is similar to the manner of positioning and securing the leader pins to the die shoe. To this end the punch head is provided with a pair of openings 25, as indicated, into which the elongated upper portion of the bushing mayfreely be inserted without contacting the side of the opening.

In practice, it has been found desirable, in assembling the die sets, to firstfrigidly secure the leader pin` in place in the die shoe as heretofore indicated, and to next place the iianged leader pin bushings onto the leader pins. 'Ihe punch holder. l is thenY set in place as indicated in Fig.

head is aligned solely by the contact of its lower face with the upper surfaces 24 of the flanges,I and is therefore perpendicular to theleaderlv therein for accommodation of the dowel pins 26 through the holes 21 in the bushing flange. Securing screws 28 may then be installed through holes 29 in the bushing flange.`

`Upon fixed assembly ofthe-parts, it will be noted that inasmuch as the leader pins are positioned perpendicularlyof the die shoe,l and -the leader pin bushings are likewiseperpendicular to the under surface of the punch holder, these respective surfaces will at all times throughout the course of their approachment and separation be retained in parallelism, wherebyv proper alignment of the punch and die is at all times assured throughout their relative reciprocation.

Of course, it will be obvious that they results hereinbefore describedV in connection with separable flanges, bushings, and leader pins could also be obtained if the flanges were to be integral with the respective leader pin or bushing. However, by the present method of assembly it' has been found that an accuracy equivalent to such integral construction can be obtained with considerable economy of time and material and corresponding reduction in expense over vthe integral manufacture of these parts. The upper end of the leader p-in may be provided with a central opening forming an oil well 30 which communicates with an oil groove 3| by means of holes 32. By this means, lubricant is distributed to the leader pin bushings at each upward movement of the punch holder. A suitable wickmay be placed in this oil Well if desired.

From the foregoing description it will be apparent to those skilled in the art that various modifications thereof may be made Without departing from the spirit and scope of this inven-l tion, and I desire, therefore, that the same Vbe limited only by the scope of the prior art and the appended claims.

Having thus described. the invention, what is claimed and vdesired to be secured by Letters Patent is:

1. A die set comprising a die shoe, a punch holder, a pair of leader pins secured to said die shoe for guiding the punch holder, guide bushings for said leader pins secured to. said punch holder, said die shoe and punch holder having plane finished surface portionssurrounding and perpendicular to the axes of said leader pins, said leader pins having laterally extending annular flanges having plane finished faces perpendicular to said axes engaging the plane nishedsurfaces of the die shoe, dowel pins engaging said flanges and die shoe for positioning the leader pins, securing screws extending through said flanges and threaded into the die shoe for holding the pins in place, said bushings having laterally extending annular flanges having plane finished faces perpendicular to the axes of said bushings and leader pins engaging. the finished surfaces of the punch holder; liowel pinsengaging said nanges and punch holder for positioning the bushings, and screws extending through saidv flanges and threaded into the punch` holder for holding the bushings in place.

2. A die set comprising a die shoe, apunch holder, a pair of leader pins -secured to said die shoe for guiding the punch holder, guide bushings for said leader pins secured to said punch holder, said die shoe and punch holder having plane finished surface portions surrounding and perpendicular to the axes of said leader pins, said leader pins' having laterally extending annular flanges having plane finished faces perpendicular to said axes engaging the plane finished surfaces of the die shoe, dowel pins engaging said flanges and die shoe for positioning the leader pins, securing screws extending through said flangesand threaded into the die shoe for holding the pinsin place, said bushings having laterally extending-annular flanges having vplane finished faces perpendicular to the axes of said bushings and leader pins engaging the finishedk surfaces of the punch holder, dowel pins engaging said flanges and punch holder for positioning the bushings, and screws extending through said flanges and threaded into the punch holder for holding the bushings in place, said die shoe having openings aligned with said leader pins and said leader pins having extensions loosely engageable' in said openings for approximately positioning the pins in assembly.

. 3; A die set comprising a die shoe, a punch holder, a pair of leader pins secured to said die shoe for guiding the punch holder, guide bushings for said leader pins secured to said punch holder, said die shoe and punch holder having plane finished surface portions surrounding and perpendicular tothe axes of said leader pins, said leader pins having laterally extending annular flanges having plane finished faces perpendicular to said axes engaging the plane iinished. surfaces of the die shoe, dowel pins engaging said flanges and die shoe for positioning the leader pins, securing screws extending through said fianges and threaded into the die shoe for holding the pins in place, said bushings having laterally extending annular flanges having plane finished faces perpendicular to the axes of said bushings and leader pins engaging the nished surfaces of the punch holder, dowel pins engaging said flanges and punch holder for positioning the bushings, and screws extending through said flanges and threaded into the punch holder foi holding the bushings in place, said punch holders having openings alignedwith said bushings and said bushings having extensions looselyengageable in said openings for approximately positioning thebushings in assembly.

4. A die set comprising a die shoe, a punch holder, a pair of leader pins secured to said die shoe for guiding the punch holder, guide bushings for said leader pins secured to said punch holder, said die shoe and punch holder having plane finished surface portions surrounding and perpendicular to the axes of said leader pins,

said leader ypins having laterally extending annular flanges having plane finished faces perpendicular to Asaid axes engaging the plane fmished surfacesv of the die shoe, dowel pins engaging said flanges and die shoe forpositioning the leader pins, securing screws extending through said flanges and threaded into the die` shoe for holding the pins in place, said bushings having laterally extending annular' flanges having plane finished faces perpendicular to the axes of said bushings land 1eader-pins engaging the finishedv surfaces of the punch holder, dowel pins engaging said kflanges and punch holder for positioning the bushings, and screws` extending through said flangesr and ,threaded into the punchholder for holding the bushings in place, said die shoe having openings aligned with said leader pins and said yleader pins having extensions loosely engageable in said openings for approximately positioning the pins in assembly, said punch holders having openings aligned with Ysaid bushings and said bushings having extensions loosely engageable in said openings for approximately positioning the bushings in assembly.l

5. A die set comprising a die shoe, a punch holder, a pair of leader vpins secured to said die shoe for guiding the punch holder, guide bushings for said leader pins secured to said punch holder, said Adie shoe and punch holder having plane finished surface portions surrounding and perpendicular to the axes of said leader pins, said leader pins having laterally extending annular flanges having plane finished faces perpendicular to said axes engaging the plane nished surfaces of the die shoe, dowel pins engaging said fianges and die shoe for positioning the leader pins, securing screws extending through said flanges and threaded into the die shoe for holding the pins in place, said bushings havinglaterally extending annular flanges having plane iinished faces perpendicular to the axes of said bushings and. leader pins engaging the finished surfaces of the punch holder, dowel pins engaging said flanges and punch holder for positioning the bushings, and screws extending through said flanges and threaded into the punch holder for holding the bushings in place, the leader pin flanges being secured on a common plane perpendicular to the axes of the leader pins and the leader pin bushing flanges being likewise secured on a common plane perpendicular tov the axes of the leader pin bushings.

6. In a die set having a die shoe and a punch holder, each provided with opposed plane nished surfaces and mounted for relative movement,

leader pins secured to said die shoe for guiding the punch holder, guide bushings for each of said leader pins secured to said holder, said leader pins and said bushings each having laterally extending flanges which are provided with plane finished surfaces perpendicular to the axes of the leader pins and .engaging the plane finished surfaces of the die shoe and punch holder, respectively, and dowel pins engaging said flanges and the adjacent punch holder or die Shoe for relatively positioning the leader pins and bushings with respect to each other and with respect to the die shoe and punch holder.

7. A die set comprising a die shoe, a punch holder, a pair of leader pins secured to said die shoe for guiding thepunch holder, guide bushings for said leader pins secured to said punch holder, said die shoe and punch holder having plane finished surface portions surrounding and perpendicular to the axes of said leader pins, said leader pins having separate laterally extending annular flanges having plane nished faces perpendicular to said axes and engaging the plane finished surfaces of the die shoe, dowel pins engaging said flanges and die shoe for positioning the leader pins, securing screws extending through said flanges and threaded into the die shoe for holding the pins in place, said bushings also having separate laterally extending annular flanges having plane finished faces perpendicular to the axes of said bushings and leader pins engaging the finished surfaces of the punch holder, dowel pins engaging said flanges and punch holder for positioning the bushings, screws extending through said anges and threaded into the punch holder for holding the bushings in place, the leader pin engaging surfaces of said flanges being provided with an annular internal groove and said vleader pins and bushings being provided with complemental external grooves for registry therewithwhen assembled, anopening leading to the hollow chamber. formed by said grooves when assembled, and a locking ring of iiowable metal positioned in said grooves to resist separation of said parts.

. 8. A die set comprising a die shoe, a punch holder, a pair of leader pins secured to said die shoe for guiding the vpunch holder, guide bushings for said leader pins secured to said punch holder, said die shoe and punch holder having opposed plane finished surface portions, said leader pins having laterally extending annular flanges with plane finished surfaces perpendicular to their axes for engagement with the plane finished surface of the die shoe, and positioning and securing means rfor said flange, said bushings likewise having laterally extending annular flanges with a plane nished surface perpendicular tothe axes of said bushings and engaging the finished surface of the punch holder, and positioning and securing means for positioning and securing said bushings with respect to the punch holder.

9. A leader pin assembly for a punch and die set comprising a leader pin having an annular groove adjacent one end, a plate having a central aperture provided with a complementary internal annulus, the central aperture in said plate being designed to closely engage the end of said leader pin adjacent said annular groove, and an opening extending to the hollow chamber formed by said annuluses when in registry, whereby when said flange is in place a iiowable metal may be directed into said opening and which when hardened'may retain the parts in their respective positions.

10. A readily replaceable leader pin bushing for a punch and die set comprising an elongated cylindrical member having an exterior of substantially uniform external dimension and an annular circumferential groove, a flange member having an opening corresponding to the outside diameter oi' said bushing, a complementary groove extending about the inner Wall of the flange, whereby said flange may be pressed over said bushing so that the grooved portions will register, and an opening vleading to said groove whereby a molten material may be inserted to fill said groove and which upon hardening lwill lock the flange upon the bushing.

11. A flanged pin construction comprising a Y flange member having an opening therein and a separate pin member fitted in said opening, said flange and said pin having complementary arcuate grooves which when in registry deiine a longitudinally closed arcuate chamber, and a'ring of molded material occupying said chamber which resists relative movement of said members.

12. A pin construction comprising a cylindrical pin member having an arcuate groove, a structural member having an opening and a corresponding complementary arcuate groove, said grooves when in registry defining an arcuate longitudinally closed space, one of said grooves being provided with an entrance opening for the admission of molten material, and a ring of molded material occupying said space to retain said grooves in registry.

EMIL A. BAUMBACH. 

